Paragloborotalia


Classification: pf_cenozoic -> spinose -> Globigerinidae -> Paragloborotalia
Sister taxa: Catapsydrax, Eoglobigerina, Globigerina, Globigerinatheka, Globorotaloides, Globoturborotalita, Guembelitrioides, Orbulinoides, Paragloborotalia, Parasubbotina, Pseudoglobigerinella, Subbotina, Turborotalita,
Daughter taxa (blue => in age window 0-300Ma)
Small, very low trochospiral, compact, subquadrate test. Aperture with a thickened continuous lip. Wall coarsely cancellate.
Test small, compact, quadrangular, usually 4 chambers in the final whorl. Umbilicus very narrow, sutures radial. Aperture with prominent lip, which often obscures the primary aperture.
Specimens which cannot be assigned to established species

Taxonomy

Citation: Paragloborotalia Cifelli, 1982
Rank: Genus
Type species: Globorotalia opima subsp. opima Bolli, 1957.
Synonyms:

Catalog entries: Paragloborotalia;

Type images:

Distinguishing features: The genus is distinguished by the very low trochospiral test and low-arched umbilical-extraumbilical aperture with a thick lip of constant thickness. There are 4-5 chambers in the ultimate whorl, and a coarsely cancellate, sacculifer-type wall.

NB The short diagnoses are used in the tables of daughter-taxa to act as quick summaries of the differences between e.g. species of one genus. They have initially been copied from the diagnostic characters/distinguishing features sections of the Eocene and Paleocene Atlases, they will be edited as the site is developed.

Description


Diagnostic characters: The genus is distinguished by the very low trochospiral test and low-arched umbilical-extraumbilical aperture with a thick lip of constant thickness. There are 4-5 chambers in the ultimate whorl, and a coarsely cancellate, sacculifer-type wall.

Wall type: Normal perforate, coarsely cancellate, sacculifer-type wall texture, spinose (Cifelli, 1982). [Olsson et al. 2006]

Test morphology: Very low trochospiral, globular, compact, subquadrate to quadrate in outline, chambers globular, much embracing; in spiral view, 4-5 globular chambers, increasing rapidly, then moderately in size, strongly embracing chambers in ultimate whorl, ultimate chamber may be reduced in size, flattened or slightly concave, sutures slightly depressed, straight; in umbilical view 4-5 globular, embracing chambers that often close off umbilicus, sutures slightly depressed, straight; in edge view periphery rounded, aperture, umbilical-extraumbilical, a low arch, bordered by a narrow, thickened lip.
[Olsson et al. 2006]

Biogeography and Palaeobiology


Phylogenetic relations: The type species of Paragloborotalia, P. opima (Bolli), is an Oligocene taxon of great biostratigraphic utility that was originally described as belonging to the non-spinose genus Globorotalia. However, in an early application of wall texture - based taxonomy, Cifelli (1982) showed that opima possesses a cancellate wall and, based on observed spine holes, must originally have been spinose. Paragloborotalia opima is descended from the closely related species P. nana, which was initially traced down to the lower Oligocene of the Cipero Formation, Trinidad by Bolli (1957b) and subsequently into the upper Eocene by Blow (1979). We have now traced it as low as Zone E7 in cores from Tanzania, although these earliest morphotypes show some transitional features to P. griffinoides n. sp. Our researches show that P. nana is part of a conservative lineage of low-trochospiral species that is rooted in the genus Parasubbotina.
Parasubbotina is a more loosely coiled genus with less embracing chambers, and its species tend to be more variable in morphology in chamber arrangement and shape, size, and wall texture; whereas Paragloborotalia has a very conservative, generalized morphology, and less variable test morphology. From its origin from Parasubbotina in Zone E1, it is represented by only two Eocene species, P. nana and P griffinoides n. sp. These are both characterized by (typically) having only 4 chambers in the ultimate whorl, an umbilical-extraumbilical aperture with a thick lip of constant thickness around the aperture, and small test size. [Olsson et al. 2006]

Most likely ancestor: Parasubbotina - at confidence level 0 (out of 5). Data source: .

Biostratigraphic distribution

Geological Range:
Last occurrence (top): at top of Burdigalian Stage (100% up, 16Ma, in Burdigalian stage). Data source: Total of range of species in this database
First occurrence (base): at base of Ypresian Stage (0% up, 56Ma, in Ypresian stage). Data source: Total of range of species in this database

Plot of occurrence data:

Primary source for this page: Olsson et al. 2006 - Atlas of Eocene Planktonic Foraminifera, chapter 5, p. 88

References:

Blow, W.H., (1979). The Cainozoic Globigerinida: A study of the morphology, taxonomy, evolutionary relationships and stratigraphical distribution of some Globigerinida (mainly Globigerinacea), 2. E. J. Brill, Leiden, 1413 pp.

Bolli, H.M., (1957). Planktonic foraminifera from the Oligocene-Miocene Cipero and Lengua formations of Trinidad, B.W.I. In: Loeblich, A.R., Jr. et al. (Editors), Studies in Foraminifera: U.S. National Museum Bulletin 215. U.S. Government Printing Office, Washington, DC, pp. 97-123.

Cifelli, R., (1982). Early Occurrences and some Phylogenetic Implications of Spiny, Honeycomb Textured Planktonic Foraminifera. Journal of Foraminiferal Research, 12(2): 105-115.

Olsson, R.K.; Pearson, P.N. & Huber, B.T., (2006). Taxonomy, biostratigraphy, and phylogeny of Eocene Catapsydrax, Globorotaloides, Guembelitrioides, Paragloborotalia, Parasubbotina, and Pseudoglobigerinella n. gen. In: Pearson, P.N. et al. (Editors), Atlas of Eocene Planktonic Foraminifera, Cushman Foundation Special Publication 41. Cushman Foundation Special Publication. 41 Allen Press, Lawrence, Kansas, pp. 67-110.


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Paragloborotalia compiled by the pforams@mikrotax project team viewed: 25-6-2018

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